Ultrasonographic Measurement of Optic Nerve Sheath Diameter

Abstract

Intracranial pressure (ICP) monitoring is crucial in critically ill patients, particularly those with traumatic brain injury, intracranial hemorrhage, or other neurological emergencies. Invasive ICP monitoring remains the gold standard; however, it carries risks such as infection, hemorrhage, and technical complications. Ultrasonographic measurement of optic nerve sheath diameter (ONSD) has emerged as a rapid, bedside, noninvasive, and reliable surrogate marker for detecting raised ICP. The optic nerve sheath is anatomically continuous with the intracranial subarachnoid space, allowing transmission of cerebrospinal fluid pressure changes to the optic nerve sheath. Therefore, measurement of ONSD using bedside ultrasound may provide valuable information regarding elevated ICP.